References of "Wilmotte, Annick"
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See detailDiversité moléculaire des cyanobactéries planctonniques dans les eaux de surface belges
Lara, Yannick ULg; Lambion, Alexandre ULg; Simon, Patricia ULg et al

Poster (2008, April 02)

Les développements massifs de cyanobactéries ou ‘blooms’ sont devenus un phénomène récurrent et de plus en plus important dans les eaux douces du monde entier durant la dernière décennie. Ces ... [more ▼]

Les développements massifs de cyanobactéries ou ‘blooms’ sont devenus un phénomène récurrent et de plus en plus important dans les eaux douces du monde entier durant la dernière décennie. Ces efflorescences présentent des risques potentiels majeurs pour la santé humaine et animale et interfèrent négativement avec l'utilisation des eaux de surface par exemple, pour le captage d'eau potable, les loisirs nautiques, l'irrigation, les exploitations piscicoles. Entre 25 et 70% des blooms sont toxiques. Comme beaucoup de pays la Belgique n'a pas échappé au problème des efflorescences de cyanobactéries toxiques, mais il y a encore relativement peu de données. Durant la dernière décennie, trois projets européens et nationaux (MIDICHIP 1999-2003, B-BLOOMS 2003-2005, B-BLOOMS 2 2007-2011) se sont intéressés à la diversité des cyanobactéries dans les eaux de surfaces belges. Nous présentons ici un arbre phylogénétique élaboré à partir d’ un pool de 249 séquences partielles du gène codant pour l’ARNr 16S obtenu à partir de 31 échantillons d’eaux belges issus de ces projets. Cet arbre représente la mise à jour d’une base de données qui constitue l’inventaire des cyanobactéries d’eaux douces belges. Cette base de données permet le suivi de l’évolution de la diversité observable de ces organismes en Belgique et la surveillance de l’apparition d’espèces tropicales comme conséquence aux changements climatiques globaux. [less ▲]

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See detailAnalyse bioinformatique de différents marqueurs génétiques pour la caractérisation taxonomique et génotypique des algues bleues.
Lara, Yannick ULg; Wilmotte, Annick ULg

Poster (2008, April)

Les cyanobactéries (ou algues bleues) sont des organismes procaryotes photosynthétiques considérés comme les ancêtres des plastes des végétaux eucaryotes. Présentes dans différents types d’habitats ... [more ▼]

Les cyanobactéries (ou algues bleues) sont des organismes procaryotes photosynthétiques considérés comme les ancêtres des plastes des végétaux eucaryotes. Présentes dans différents types d’habitats terrestres ou aquatiques, elles peuvent produire des composés bioactifs d’intérêt pour des industries pharmaceutiques, ou encore des toxines présentant un risque potentiel pour la santé humaine et animale. Il est donc important de pouvoir caractériser différentes espèces et différents génotypes de ces organismes de manière indubitable pour pouvoir détecter leur présence/absence, évaluer leur rôle au sein de leur écosystème, ainsi que l’influence des facteurs environnementaux sur leur cycle de vie. La caractérisation taxonomique des cyanobactéries a longtemps été réalisée par l’étude des critères morphologiques. Cependant cette approche s’avère délicate quand ces critères peuvent être altérés par la mise en culture. De plus, cette approche requiert une expérience importante et ne permet pas de différencier des génotypes toxiques. La séquence du gène codant pour l’ARN ribosomique 16S est utilisée pour différencier les cyanobactéries jusqu’au genre et parfois jusqu’à l’espèce. Mais, dans certains cas, elle ne coïncide ni avec la description morphologique spécifique, ni avec la production de certaines toxines. Dans le cadre de cette étude, nous proposons d’évaluer l’information taxonomique et génotypique de marqueurs génétiques singuliers présents dans les génomes de cyanobactéries séquencés d la base de données Genbank. Les distances génétiques entre les parties de 32 génomes suffisamment conservées pour être alignées ont été mesurées. Ces distances ont ensuite été comparées par régression linéaire aux distances génétiques de différents loci précis (ARNr 16S, kaiC, lexA, rpoC1, recA). Les résultats préliminaires montrent un R2 de 0,9141 pour la régression linéaire entre les distances génétiques du gène recA et des régions conservées des génomes séquencés appartenant au genre Prochlorococcus. Ce résultat suggère que recA serait potentiellement un bon marqueur pour génotyper des organismes du genre Prochlorococcus. [less ▲]

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See detailAbundance and diversity of picocyanobacteria in High Arctic lakes and fjords
Van Hove, Patrick; Vincent, Warwick; Galland, Pierre et al

in Algological Studies (2008), 168

A series of meromictic lakes, stratified fjords and freshwater lakes at the northern limit of the Canadian High Arctic (northern coastline of Ellesmere Island, Nunavut) were sampled at different depths to ... [more ▼]

A series of meromictic lakes, stratified fjords and freshwater lakes at the northern limit of the Canadian High Arctic (northern coastline of Ellesmere Island, Nunavut) were sampled at different depths to quantify the presence of cyanobacteria and to describe their molecular diversity. The sampled ecosystems spanned a wide span of physico-chemical conditions, with conductivities ranging from freshwater (0.2 mS·cm−1) to seawater (48 mS·cm−1) and temperatures ranging from - 1.91 to 12°C. Fluorescence microscopy cell counts showed that picocyanobacteria occurred in high concentrations (103 to 2.5 × 104 cells·ml−1) in the oxic and suboxic zones of all of these waters. Molecular analysis of the 16S rRNA gene using Denaturating Gradient Gel Electrophoresis (DGGE) and clone libraries of samples from 8 different lakes and fjords revealed a low diversity of picocyanobacteria affiliated to the genus Synechococcus. In total, 132 short sequences from DGGE bands, clones and strains were obtained. Most of the sequences (83 %) clustered in two closely related groups that tend to separate according to saline or freshwater conditions. However, some representatives of each OTU were found in different types of habitat, suggesting some degree of tolerance. These results show that picocyanobacteria are widely distributed under a broad range of physical and chemical conditions in the Arctic environment, and that some genotypes may be specialists that occupy specific habitat types [less ▲]

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See detailCyanobacteria in microbial mats of Antarctic lakes (East Antarctica) - A microscopical approach
Taton, Arnaud; Hoffmann, Lucien; Wilmotte, Annick ULg

in Algological Studies (2008), 168

The cyanobacterial diversity in microbial mats of 56 lakes located in the Larsemann Hills and Bølingen Islands (East Antarctica) was studied by light microscopy. Thirty taxa belonging to 13 genera of ... [more ▼]

The cyanobacterial diversity in microbial mats of 56 lakes located in the Larsemann Hills and Bølingen Islands (East Antarctica) was studied by light microscopy. Thirty taxa belonging to 13 genera of Chroococcales, Oscillatoriales and Nostocales were described. Photomicrographs of the different taxa are provided and their taxonomical assignment as well as their ecology and distribution are discussed. In addition, a semi-quantitative estimation of the abundance of the different morphotypes in the samples was realized and correlated with the mat physiognomy. [less ▲]

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See detailCovariation between zooplankton community composition and cyanobacterial community dynamics in Lake Blaarmeersen (Belgium)
van Gremberghe, Ineke; Van Wichelen, Jeroen; Van der Gucht, Kathleen et al

in FEMS Microbiology Ecology (2008), 63

The cyanobacterial community composition in the mesotrophic Lake Blaarmeersen was determined by denaturing gradient gel electrophoresis (DGGE) of PCRamplified 16S rRNA gene fragments during two ... [more ▼]

The cyanobacterial community composition in the mesotrophic Lake Blaarmeersen was determined by denaturing gradient gel electrophoresis (DGGE) of PCRamplified 16S rRNA gene fragments during two consecutive years to assess the importance of different classes of explanatory variables (bottom-up and top-down factors, physical variables and phytoplankton) in cyanobacterial community dynamics. The most dominant cyanobacteria in Lake Blaarmeersen were Synechococcus (three genotypes), Limnothrix redekei and Anabaena/Aphanizomenon. Analyses of Similarity revealed that the cyanobacterial community in Lake Blaarmeersen differed significantly between the growing season and the winter season as well as between the epilimnion and hypolimnion during the stratified periods. Mantel tests revealed significant correlations between the DGGE data and bottom-up factors, physical variables, the phytoplankton community composition and, interestingly, the zooplankton community composition. In general, the zooplankton community composition (especially the cladoceran community) was more important in structuring the cyanobacterial community than the total zooplankton biomass. This study shows that grazing zooplankton communities can have a relatively strong impact on the cyanobacterial community dynamics and that this impact can be equally important as bottom-up processes regulated by nutrient concentrations and/or physical variables. [less ▲]

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See detailMicrobial communities and carbon fluxes
Warwick, Vincent F; Pedro-Alios, Carlos; Curtis, Suttle et al

in Barber, David; Michaud, Josée; Fortier, Louis (Eds.) On thin ice: a synthesis of the Canadian Arctic Shelf Exchange Study (CASES) (2008)

The CASES program has provided a remarkable opportunity to examine the community structure and seasonal dynamics of microbial communities within coastal Arctic Ocean waters. Through the microbial ... [more ▼]

The CASES program has provided a remarkable opportunity to examine the community structure and seasonal dynamics of microbial communities within coastal Arctic Ocean waters. Through the microbial component of this program, we were able to study the diversity and activities of many forms of microscopic life, including viruses, Archea and Bacteria (known collectively as prokaryotes), and Eukarya (single-celled members, also known as protists). [less ▲]

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See detailDIVERSITY AND HOST SPECIFICITY OF AZOLLA CYANOBIONTS
Papaefthimiou, Dimitra; Van Hove, Charles; Lejeune, André et al

in Journal of Phycology (2008), 44

A unique, hereditary symbiosis exists between the water fern Azolla and cyanobacteria that reside within a cavity in the dorsal leaf-lobe of the plant. This association has been studied extensively, and ... [more ▼]

A unique, hereditary symbiosis exists between the water fern Azolla and cyanobacteria that reside within a cavity in the dorsal leaf-lobe of the plant. This association has been studied extensively, and questions have frequently been raised regarding the number and diversity of cyanobionts (cyanobacterial symbionts) among the different Azolla strains and species. In this work, denaturating gradient gel electrophoresis (DGGE) and a clone library based on the 16S rRNA gene were used to study the genetic diversity and host specificity of the cyanobionts in 35 Azolla strains covering a wide taxonomic and geographic range. DNA was extracted directly from the cyanobacterial packets, isolated after enzymatic digestion of the Azolla leaves. Our results indicated the existence of different cyanobiont strains among Azolla species, and diversity within a single Azolla species, independent of the geographic origin of the host. Furthermore, the cyanobiont exhibited host-species specificity and showed most divergence between the two sections of genus Azolla, Azolla and Rhizosperma. These findings are in agreement with the recent redefinition of the taxon Azolla cristata within the section Azolla. With regard to the taxonomic status of the cyanobiont, the genus Anabaena of the Nostocaceae family was identified as the closest relative by this work. [less ▲]

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See detailAstrobiologie
Javaux, Emmanuelle ULg; Claeys, Philippe; Dehant, Véronique et al

Learning material (2008)

powerpoint sur MyULg, notes partielles imprimées

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See detailAllochthonous inputs of riverine picocyanobacteria to coastal waters in the Arctic Ocean
Waleron, M.; Waleron, Krzysztof ULg; Vincent, W. F. et al

in FEMS Microbiology Ecology (2007), 59(2), 356-365

The observed onset of climate change at high northern latitudes has highlighted the need to establish current baseline conditions in the Arctic Ocean, and has raised concern about the potential for the ... [more ▼]

The observed onset of climate change at high northern latitudes has highlighted the need to establish current baseline conditions in the Arctic Ocean, and has raised concern about the potential for the invasion and growth of biota that have warm temperature optima, such as cyanobacteria. In this study, we used 16S rRNA gene sequences as a molecular marker to evaluate the hypothesis that Arctic rivers provide a major inoculum of cyanobacteria into the coastal Arctic Ocean. Surface samples were collected along a transect extending from the Mackenzie River (Northwest Territories, Canada), across its estuary, to 200 km offshore at the edge of the perennial Arctic pack ice (Beaufort Sea). The highest picocyanobacteria concentrations occurred in the river, with concentrations an order of magnitude lower at offshore marine stations. The 16S rRNA gene clone libraries of five surface samples and five strains along this gradient showed that the cyanobacterial sequences were divided into eight operational taxonomic units (OTUs), six OTUs closely related to freshwater and brackish Synechococcus and two OTUs of filamentous cyanobacteria. No typically marine Synechococcus sequences and no Prochlorococcus sequences were recovered. These results are consistent with the hypothesis of an allochthonous origin of picocyanobacteria in the coastal Arctic Ocean, and imply survival but little net growth of picocyanobacteria under the present conditions in northern high-latitude seas. [less ▲]

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See detailCyanobacteria in cold environments
Zakhia, Frederic; Jungblut, Anne-Dorothee; Taton, Arnaud et al

in Margesin, Rosi; Schinner, Frederic; Marx, Jean-Claude (Eds.) et al 'Psychrophiles: from Biodiversity to Biotechnology (2007)

Cyanobacteria evolved under the harsh conditions of the Precambrian and their modern representatives retain a remarkable ability to adapt to and survive within extreme conditions. They dominate ... [more ▼]

Cyanobacteria evolved under the harsh conditions of the Precambrian and their modern representatives retain a remarkable ability to adapt to and survive within extreme conditions. They dominate terrestrial and freshwater cold ecosystems of the Arctic, Antarctic and alpine regions, even though they do not seem to be specifically adapted to optimal growth at low temperatures. They play a major ecological role as they often are primary colonisers of substrates and major primary producers in these ecosystems. The application of molecular tools in combination with classic morphological techniques has begun to provide new insights into the real diversity of cyanobacteria and their biogeographical distribution in cold environments. Our survey of recent studies suggests complex distributional patterns of cyanobacteria, with cosmopolitan, endemic, and habitat-specific genotypes. This ongoing research will help to identify specific geographical areas that have unique microbial communities. However, many more studies are needed to unravel the enormous diversity of cyanobacteria and to better define their biogeographical patterns in cold environments. This is an urgent task in view of the climatic changes that will undoubtedly alter the structure and functioning of microbial communities in polar and alpine ecosystems. [less ▲]

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See detailMorphological and molecular characterization of planktonic cyanobacteria from Belgium and Luxembourg
Willame, R.; Boutte, C.; Grubisic, Stana ULg et al

in Journal of Phycology (2006), 42(6), 1312-1332

For the first time in Belgium and Luxembourg, the diversity and taxonomy of 95 cyanobacterial strains isolated from freshwater blooms were assessed by the comparison of phenotypes and partial 16S rRNA ... [more ▼]

For the first time in Belgium and Luxembourg, the diversity and taxonomy of 95 cyanobacterial strains isolated from freshwater blooms were assessed by the comparison of phenotypes and partial 16S rRNA gene sequences. The results showed the high diversity of nanoplanktonic, picoplanktonic, and benthic-periphytic cyanobacteria accompanying the main bloom-forming taxa. Indeed, besides 15 morphotypes of bloom-forming taxa, seven non-bloom-forming planktonic morphotypes and 11 morphotypes from benthic-periphytic taxa were isolated in culture from the plankton samples of 35 water bodies. The bloom-forming strains belonged to the genera Microcystis, Woronichinia, Planktothrix, Anabaena, and Aphanizomenon, whereas the other strains isolated from the same samples were assigned to the nanoplanktonic Aphanocapsa, Aphanothece, Snowella, and Pseudanabaena; to the picoplanktonic Cyanobium; and to the benthic periphytic Geitlerinema, Komvophoron, Leptolyngbya, Lyngbya, Phormidium, Calothrix, Nostoc, and Trichormus. The results supported both the polyphyletism of genera such as Aphanocapsa, Aphanothece, Leptolyngbya, Geitlerinema, Anabaena, and Aphanizomenon as well as the validity of genera such as Microcystis, Planktothrix, and Pseudanabaena with gas vesicles and cells constricted at the cross wall. The results obtained showed the close relationship between Snowella and Woronichinia for which very few sequences exist. The first sequence of Komvophoron appeared poorly related to other available cyanobacterial sequences. Although in a few cases a good agreement existed between phenotypic and genotypic features, there was generally a discrepancy. Strains with identical morphotypes show small differences in the 16S rRNA sequences, which might be related to the different chemical properties of their habitats. The results showed the importance of the polyphasic approach in order to improve the taxonomy of cyanobacteria. [less ▲]

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See detailPolyphasic study of Antarctic cyanobacterial strains
Taton, A.; Grubisic, Stana ULg; Ertz, D. et al

in Journal of Phycology (2006), 42(6), 1257-1270

We isolated 59 strains of cyanobacteria from the benthic microbial mats of 23 Antarctic lakes, from five locations in two regions, in order to characterize their morphological and genotypic diversity. On ... [more ▼]

We isolated 59 strains of cyanobacteria from the benthic microbial mats of 23 Antarctic lakes, from five locations in two regions, in order to characterize their morphological and genotypic diversity. On the basis of their morphology, the cyanobacteria were assigned to 12 species that included four Antarctic endemic taxa. Sequences of the ribosomal RNA gene were determined for 56 strains. In general, the strains closely related at the 16S rRNA gene level belonged to the same morphospecies. Nevertheless, divergences were observed concerning the diversity in terms of species richness, novelty, and geographical distribution. For the 56 strains, 21 operational taxonomic units (OTUs, defined as groups of partial 16S rRNA gene sequences with more than 97.5% similarity) were found, including nine novel and three exclusively Antarctic OTUs. Sequences of Petalonema cf. involvens and Chondrocystis sp. were determined for the first time. The internally transcribed spacer (ITS) between the 16S and the 23S rRNA genes was sequenced for 33 strains, and similar groupings were observed with the 16S rRNA gene and the ITS, even when the strains were derived from different lakes and regions. In addition, 48 strains were screened for antimicrobial and cytotoxic activities, and 17 strains were bioactive against the gram-positive Staphylococcus aureus, or the fungi Aspergillus fumigatus and Cryptococcus neoformans. The bioactivities were not in coincidence with the phylogenetic relationships, but rather were specific to certain strains. [less ▲]

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See detailThe cyanophyte Arthrospira fusiformis from Mozambique, Africa: Morphological and molecular characterization
Mussagy, Aidate; Wilmotte, Annick ULg; Cronberg, Gertrud

in Algological Studies (2006), 121

The morphology and the Internally Transcribed Spacer sequences of two Arthrospira (Cyanobacteria) strains with tightly coiled and loosely coiled trichome, isolated from waste water treatment ponds in ... [more ▼]

The morphology and the Internally Transcribed Spacer sequences of two Arthrospira (Cyanobacteria) strains with tightly coiled and loosely coiled trichome, isolated from waste water treatment ponds in Maputo, Mozambique, were investigated. According to the accepted traditional classification the tightly coiled strains were assigned as Arthrospira fusiformis and the loosely coiled as Arthrospira maxima. In both clonal cultures, initiated from a tightly coiled (strain 1) or a loosely coiled trichome (strain 2), different variants arose, in which the tightly coiled forms were more lax than the inoculated cloned trichomes, and loosely coiled forms became tightly coiled. In both cultures, different transient forms appeared, and even straight trichomes were observed. The straight form (variant 1) was isolated and cultivated under different light intensities. After two months, this straight form had not changed into coiled trichomes. However, the trichomes obtained after growth of the hormogonia of the straight trichomes contained a mixture of loosely coiled and straight trichomes.On the basis of the morphological analysis of Arthrospira, it is evident that the degree of coiling is highly variable, which creates uncertainty when used to define the different species. The DNA from the two clonal strains 1 and 2 was isolated and a part of the rRNA operon (including the 3' end of the 16S rRNA gene and the Internally Transcribed Spacer) was determined after amplification by PCR using specific primers. The two ITS sequences were identical and belonged to the subcluster I.A., as defined by Baurain et al. (2002). Variant 1 gave also an identical ITS sequence. A PCR to test the presence of mcyE, a gene involved in the synthesis of the microcystin synthetase, was negative for the two strains and the variant 1. This study showed that for a reliable identification of Arthrospira species, information from specimens collected in the field, cultured strains, developmental stages, and molecular analysis, should be combined. [less ▲]

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See detailBiogeographical distribution and ecological ranges of benthic cyanobacteria in East Antarctic lakes
Taton, A.; Grubisic, Stana ULg; Balthasart, Pierre ULg et al

in FEMS Microbiology Ecology (2006), 57(2), 272-289

For the first time, the cyanobacterial diversity from microbial mats in lakes of Eastern Antarctica was investigated using microscopic and molecular approaches. The present study assessed the ... [more ▼]

For the first time, the cyanobacterial diversity from microbial mats in lakes of Eastern Antarctica was investigated using microscopic and molecular approaches. The present study assessed the biogeographical distribution of cyanobacteria in Antarctica. Five samples were taken from four lakes spanning a range of different ecological environments in Larsemann Hills, Vestfold Hills and Rauer Islands to evaluate the influence of lake characteristics on the cyanobacterial diversity. Seventeen morphospecies and 28 16S rRNA gene-based operational taxonomic units belonging to the Oscillatoriales, Nostocales and Chroococcales were identified. The internal transcribed spacer was evaluated to complement the 16S rRNA gene data and showed similar but more clear-cut tendencies. The molecular approach suggested that potential Antarctic endemic species, including a previously undiscovered diversity, are more abundant than has been estimated by morphological methods. Moreover, operational taxonomic units, also found outside Antarctica, were more widespread over the continent than potential endemics. The cyanobacterial diversity of the most saline lakes was found to differ from the others, and correlations between the sampling depth and the cyanobacterial communities can also be drawn. Comparison with database sequences illustrated the ubiquity of several cyanobacterial operational taxonomic units and their remarkable range of tolerance to harsh environmental conditions. [less ▲]

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See detailTesting of primers for the study of cyanobacterial molecular diversity by DGGE
Boutte, C.; Grubisic, Stana ULg; Balthasart, Pierre ULg et al

in Journal of Microbiological Methods (2006), 65(3), 542-550

Denaturing Gradient Gel electrophoresis (DGGE) is a PCR-based technique which is widely used in the study of microbial communities. Here, the use of the three specific 16S rRNA cyanobacterial specific ... [more ▼]

Denaturing Gradient Gel electrophoresis (DGGE) is a PCR-based technique which is widely used in the study of microbial communities. Here, the use of the three specific 16S rRNA cyanobacterial specific primers CYA359F, CYA781R(a) and CYA781R(b) on the assessment of the molecular diversity of cyanobacterial communities is examined. Assignments of the reverse primers CYA781R(a) and CYA781R(b) with cyanobacterial strain sequences showed that the former preferentially targets filamentous cyanobacteria whereas the latter targets unicellular cyanobacteria. The influence of the GC clamp position on the forward Or on reverse primer and the use of the two reverse primers separately or in equimolar mixture were investigated. Three environmental samples were subjected to amplification with 6 combinations of primers. The 6 banding patterns as well as the sequences of the bands extracted were analysed and compared. In addition, to assess the effect of the position of the GC clamp, the melting profiles of the sequences of Aphanizomenon flos-aquae PMC9707 and Synechococcus sp. MH305 were determined, with the GC clamp in the 3' or 5' position. Results showed that the use of two separate amplifications allowed a more complete study of the molecular diversity of the cyanobacterial community investigated. Furthermore, similar richness and identical phylogenctic assignments of extracted bands were obtained irrespective of the positioning of the GC clamp. (c) 2005 Elsevier B.V. All rights reserved. [less ▲]

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See detailUltrastructure and taxonomic position of two species of the cyanobacterial genus Schizothrix
Komarek, J.; Taton, A.; Sulek, J. et al

in Cryptogamie Algologie (2006), 27(1), 53-62

The cyanobacterial genus Schizothrix is traditionally classified in the special family Schizotrichaceae (order Oscillatoriales) according to the structure of the filaments and thallus: one, two, or more ... [more ▼]

The cyanobacterial genus Schizothrix is traditionally classified in the special family Schizotrichaceae (order Oscillatoriales) according to the structure of the filaments and thallus: one, two, or more ensheathed and fasciculated trichomes are enveloped by common sheaths. The fine Structure of cells and filaments of two natural populations of typical Schizothrix-species (S. facilis, S lacustris) were investigated in our Study. The ultrastructure of trichomes was found to be similar to the pseudartabaenacean types (thylakoid arrangement, inclusions, cell wall), and indicates the close relationship to this group of simple filamentous cyanobacteria. The special life form, which was considered as the most important phenotypic intergeneric (and interfamilial) differentiating character was proven: Fasciculated trichomes are enveloped by their own sheaths, and form (usually heteropolar) filaments enveloped by mother common sheath. However, in spite of the fact that the ultrastructure and morphology of trichomes were found to be similar to other pseudanabacnacean types, the relationship to Pseudanabaenaceae must await detailed molecular studies to be more completely evaluated. The first molecular results concerning a few Schizothrix-like strains from Antarctica show that most belong to a cluster, which is separated from the other oscillatorian clusters. This could support the genetic basis of the Schizothrix genus. [less ▲]

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See detailMicrobial ecology of the closed artificial ecosystem MELiSSA (Micro-Ecological Life Support System Alternative): Reinventing and compartmentalizing the Earth's food and oxygen regeneration system for long-haul space exploration missions
Hendrickx, Larissa; De Wever, Heleen; Hermans, Veronik et al

in Research in Microbiology (2006), 157

MELiSSA is a bioregenerative life support system designed by the European Space Agency (ESA) for the complete recycling of gas, liquid and solid wastes during long distance space exploration. The system ... [more ▼]

MELiSSA is a bioregenerative life support system designed by the European Space Agency (ESA) for the complete recycling of gas, liquid and solid wastes during long distance space exploration. The system uses the combined activity of different living organisms: microbial cultures in bioreactors, a plant compartment and a human crew. In this minireview, the development of a short-cut ecological system for the biotransformation of organic waste is discussed from a microorganism's perspective. The artificial ecological model—still in full development—that is inspired by Earth's own geomicrobiological ecosystem serves as an ideal study object on microbial ecology and will become an indispensable travel companion in manned space exploration. [less ▲]

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See detailBiogeographic trends in Antarctic lake communities
Gibson, John; Wilmotte, Annick ULg; Taton, Arnaud et al

in Bergstrom, Dana; Convey, Peter; Huiskes, Ad HL (Eds.) Trends in Antarctic terrestrial and limnetic ecosystems (2006)

The basic biogeographic zones proposed many years ago – the Subantarctic islands, Maritime Antarctica and Continental Antarctica – continue to hold up, though they cannot be seen as absolute dividers of ... [more ▼]

The basic biogeographic zones proposed many years ago – the Subantarctic islands, Maritime Antarctica and Continental Antarctica – continue to hold up, though they cannot be seen as absolute dividers of biodiversity. For example, subantarctic Macquarie Island appears to be biogeographically separate from the islands of the Kerguelen Province, and on the continent there are species that are present in lakes of more than one zone. Furthermore, there are numerous lake environments that have yet to be investigated, and it is probable that some of these lakes could turn up surprises that will bring into question these basic divisions. An important question to be answered is whether these biogeographic zones reflect climate attributes, or whether they were moulded long ago by barriers to dispersal. Again, our imperfect knowledge of Antarctic lacustrine biogeography means that this question cannot at present be answered. However, as discussed elsewhere in this volume (Chown and Convey), there are indications of a strong biogeographical boundary for terrestrial species between the Maritime and Continental Antarctic zones. A palaeolimnological approach will assist in answering this question: understanding how Antarctic biogeography has developed through time will provide necessary insights into current distributions. A prime example is the occurrence of the copepod Boeckella poppei in Beaver Lake. Pugh et al. (2002) initially concluded that this species was an anthropogenic introduction, then Bayly et al. (2003) provided morphological evidence for long habitation in the area of Beaver Lake. Recent palaeolimnological work has shown that the species has been present in nearby Lake Terrasovoje for at least 9000 yrs (L. Cromer, A. Bissett, J. Gibson and K. Swadling, unpublished data). Even though this lake has only existed in the Holocene, cosmogenic exposure dates in the same area of exposed rock can exceed 106 years (D. Gore and D. White, personal communication). From these observations it can be concluded that Boeckella poppei has been associated with the Beaver Lake area for at least the entire Holocene and probably well back into the Pleistocene, and that its occurrence outside its ‘preferred’ biogeographical zone (Maritime Antarctica) is not a reflection of current climate, rather of history. The majority of our knowledge regarding Antarctic lacustrine biodiversity and biogeography has come from classic taxonomic studies, where the morphology (or biochemistry for bacteria) has been of greatest importance. In many cases this has led to questionable identification, correct identification of species is paramount if the true biodiversity and biogeography of Antarctica is to be deduced. It is only in the last few years that the more objective approach of molecular genetics has been applied to Antarctic lacustrine organisms, and then only for more cryptic groups, such as bacteria and cyanobacteria. As more samples and organisms are studied by these methods it is likely that new relationships between species distributions will be found. Due to the limited number of species in Antarctica (compared to more temperate zones), it may be possible in the future to record the make-up of selected genes of most, if not all, of the biota, which will allow more precise analysis. There is increasing evidence for endemism amongst the inhabitants of lakes both on the Antarctic continent and the subantarctic islands, from bacteria to crustacea. Use of molecular genetic techniques to identify more cryptic species will most likely add to the list of putative endemics. It is clear, however, that recent colonisation and current climate also play important roles in the distribution of the biota, as most of the lakes in Antarctica are of relatively recent (Holocene) origin. Colonising species have to be adapted to transport from source areas, which can either involve inter- or intra-continental movement, as well as survival on arrival at potential habitat. Flexibility in nutritional and habitat requirements is an important factor in determining whether a species will be a successful coloniser. The buffering to environmental extremes provided by the liquid water habitat means that conditions further south will not be as harsh as those experienced by their terrestrial counterparts. As the climate changes in the future, it will be interesting to note the effects of these changes on the lacustrine biota. Will new species colonise the Antarctic Peninsula where temperatures are warming? In the longer term, the biogeography of Antarctic lakes will continue to be dynamic. New species will arrive, others will become extinct. The biogeographic zones long-proposed may continue to hold, though more precise knowledge of current distributions and responses to climate change may refine our view. [less ▲]

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